NEW YORK (TheStreet) -- May 6 is the fifth anniversary of the "Flash Crash," which rocked U.S. markets and dropped the Dow Jones Industrial Average by roughly 9% before equities recovered. The Department of Justice announced 22 criminal counts when Navinder Singh Sarao was arrested. 

Speaking Thursday at the Milken Institute Global Conference in Los Angeles, Terry Duffy said the futures market is not to blame for the Flash Crash. 

Stocks were already down, news out of Greece was bearish and at some point certain stocks were trading for 1 cent because the exchanges stopped providing quotes, said Duffy, the executive chairman and president of CME Group (CME - Get Report). 

So everyone blamed the futures market since they didn't know what was really going on, said Duffy. Perhaps in a bit of poor timing, the CME Group was actually in communication with Sarao the day of the Flash Crash.

However, Duffy says it wasn't because of his trading actions that day but to issue a warning for the way he was entering orders in 2008 and 2009. 

CME Chart
CME Group CME data by YCharts

CME Group is cooperating with regulators, Duffy said. Market integrity is "of the utmost importance" to both himself and the entire organization because without it "the market loses its credibility." 

While it's easy to focus on the negative things, the market has come a long way since the "crash." There's far more liquidity, increased efficiency and a more level playing field now that everyday investors can play alongside the big boys with the help of electronic trading, Duffy said.